The subject matter of the present invention relates to a method and apparatus for running a dual coiled tubing test string into a wellbore, pumping a kill fluid into an annular space located between the two coiled tubing strings, and performing a drill stem test.
Coiled tubing is increasing in popularity in connection with wellbore operations simply because it is easier and less expensive to lower a coiled tubing into a wellbore instead of a production tubing. For example, U.S. Pat. No. 5,287,741 to Schultz et al discloses a method for performing a drill stem test by lowering a coiled tubing and an attached drill stem test tool string into a production tubing string in a wellbore. The disclosure of U.S Pat. No. 5,287,741 to Schultz et al is incorporated by reference into the specification of this application. Although the Schultz patent indicates (in column 8, line 15) that the coiled tubing has no connections to leak, the coiled tubing may, nevertheless, separate thereby forming a hole. When the coiled tubing is carrying a formation fluid, the formation fluid may begin to leak through the hole in the coiled tubing. The Schultz patent fails to disclose any method or apparatus for protecting the coiled tubing and containing the leak of the formation fluid which is leaking through the hole in the coiled tubing. Consequently, a new drill stem test apparatus is needed which utilizes a coiled tubing instead of a production tubing to lower a drill stem test tool string into a wellbore, and which further includes a separate containment apparatus for preventing a formation fluid from leaking through a hole in the coiled tubing. When the new drill stem test apparatus is used in a wellbore, a new method for performing a drill stem test could be practiced in the wellbore.